TITLE:   GCN CIRCULAR
NUMBER:  39473
SUBJECT: GRB 250225B: Swift detection of a burst
DATE:    25/02/25 20:00:29 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>

M. A. Williams (PSU), S. Dichiara (PSU), R. Gupta (NASA GSFC),
H. A. Krimm (NSF), M. J. Moss (GSFC), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 19:39:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 250225B (trigger=1291459).  Swift could not slew immediately
due to an observing constraint.
The BAT on-board calculated location is 
RA, Dec 306.145, -41.484 which is 
   RA(J2000) = 20h 24m 35s
   Dec(J2000) = -41d 29' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multiple-peaked
structure (well-separated peaks at T+1, T+60, T+110) with a total
duration of about 120 sec. The peak count rate was ~13000 counts/sec 
(15-350 keV), at ~1 sec after the trigger.

Due to a Moon observing constraint, Swift cannot slew to the BAT
position until 05:11 UT on 2025 February 26. There will thus be no XRT
or UVOT data for this trigger before this time.

We note the presence of the Emission-line Galaxy ESO 340-26
in the BAT error box.  This is a bright (B=14.8, R=10.9) extended
(1.4 arcmin) galaxy at z ~ 0.018 .

Burst Advocate for this burst is M. A. Williams (mjw6837 AT psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)